SS/CM barrel life.

For the record, I have a Shilen stainless select match barrel in 416 (6.5x284) on order from Jim at NSS. I have been waiting on it for a while like many others this year.

My primary reason for picking stainless is that it survives accidental exposure to moisture and condensation a lot more gracefully than CM. Given that most of the hunting season here in MI it is typically 30F or more colder outside than inside one tends to have severe issues with condensation and even frost coating all metal parts of the weapon. With a CM weapon, I would basically have to remove the receiver from the stock every time I get back home to dry it out with a hair dryer and then re-oil it to prevent rust. That sounds like a high maintenance relationship to me. Where I live I can't just leave my rifles on the porch all winter either...

Knowing the differences between 416 and 4140 I know to let the barrel cool between shots and not to use it for high volume shooting like prairie dogs. Even so I should expect to see accuracy go south by the time I get to 1500 rounds if not before. My similarly equipped 243 AI with another Shilen select match barrel might make it to 2000 rounds. My similarly equipped 308 Win will probably last a long time... There is not really a lot that one can do about these things. Practice with the 308 and spare the others for "real work"...

As far as throat erosion stainless tends to do better because it absorbs heat slower , as well as releasing it, and suffers less fatigue during expansion at moderate temperatures. Even though it is not by much.

4140 is capable of much higher strength and hardness when tempered, but experiences cracks throughout the surface of the throat as the rapid expansion and contraction during shot strings and begings to erode quickly. As well as its tendancy to react with the very corosive properties of modern powder under high heat and pressure. This is why they are so often chrome lined.

Although these differences are minor and present it would not keep me from buying a carbon steel barrel.

Owning a 6.5x284 is like driving a dragster. It goes really fast, but its not going to get to 100 000 miles on the odo... Everything in life has its price. If all our equipment was meant to last forever, life would be pretty boring. Sometimes one has to live it up a little...

As a Heat Treater by trade and an owner of a 6.5/284 I went with stainless.
As to the previous comments about the difference between 300 and 400 series stainless steels, you are correct. They are 2 totally different animals. 300 series being the Austenitic type and can only be work hardened. 400 series is Martensitic type that can easily be hardened through conventional heat treating. Everything the Bushman said was correct, but I chose the SS barrel for the possibility of lessening the throat erosion problem of this speedster of a cartridge.
On a less geeky note, it sure is fun to shoot!